FPDs are widely used in modem display devices due to their advantages such as portability, low power consumption, and low radiation. Generally, an FPD includes a key switch system. The key switch system is used to turn on and turn off the FPD.
FIG. 9 is a perspective view of a conventional FPD. The FPD 100 includes a display module 110, a supporting member 120 configured to engage with and support the display module 110, and a base 130 configured to hold the supporting member 120. The display module 110 includes a front frame 11, a display panel 12, a key switch system 13, and a back shell 14. The front frame 11 and the back shell 14 are opposite to each other, and cooperatively form an accommodating space for receiving the display panel 12. The front frame 11 surrounds a display screen of the display panel 12. The front frame 11 includes a though hole 125 disposed in a middle region of a bottom border thereof. The through hole 125 is configured to partly receive the key switch system 13.
FIG. 10 is an isometric, exploded view of the key switch system 13. The key switch system 13 includes a keycap 15, an elastic member 17, and a printed circuit board (PCB) 19. The keycap 15 includes an end wall 151, and is typically made of lightproof material. The PCB 19 includes an indicator lamp 191 and a key switch 192 thereon. The key switch 192 is electrically coupled to a controller (not shown) in the FPD 100, and is used for turning on and turning off the FPD 100. The indicator lamp 191 is configured to indicate a working status of the FPD 100.
The elastic member 17 includes a main body 171, a keycap receptacle 172, a light cover 173, and a key bar 174. The main body 171 is made of elastic material, and includes a fixing portion 179 and a free portion 170. The fixing portion 179 is configured to fix the main body 171 to the front frame 11. The keycap receptacle 172 is made of transparent resin, and includes a cylindrical sidewall 176. The cylindrical sidewall 176 defines a round groove (not labeled) for receiving the keycap 15. The keycap receptacle 172 is disposed at one side of the free portion 170, and both of the light cover 173 and the key bar 174 are disposed at an opposite side of the free portion 170. The light cover 173 is configured to prevent light beams emitted by the indicator lamp 191 from emitting upwards and causing light leakage. The key bar 174 is configured to directly press the key switch 192.
Also referring to FIG. 11, in assembly, the elastic member 17 is fixed to an inner surface of the front frame 11 via the fixing end 179, with the keycap receptacle 172 disposed in the through hole 125. The keycap 15 is engaged to and received in the round groove of the keycap receptacle 172, thereby the keycap 15 is surrounded by the cylindrical sidewall 176. The PCB 19 is moved towards the elastic member 17, so that the indicator lamp 191 is disposed below the light cover 173, and the key switch 192 contacts the key bar 174 without any pressing force.
In operation, when the FPD 100 is turned on, the keycap 15 is pressed in, and this causes the main body 171 to be elastically deformed. The key bar 174 is forced to press the key switch 192, such that the key switch 192 is switched on. Then a control signal provided by a peripheral circuit is sent to the controller via the key switch 192. Upon receiving the control signal, the controller controls the FPD 100 to start to function, and simultaneously provides a voltage signal to the indicator lamp 191. The voltage signal drives the indicator lamp 191 to emit light beams. Most of the light beams are transmitted to the keycap 15. Because the keycap 15 including the end wall 151 is made of lightproof material, the light beams are prevented from emitting from the keycap 15 through the end wall 151. Only a few light beams transmit to the sidewall 176 of the keycap receptacle 172, and then emit from an end of the sidewall 176. Thereby, a light pattern is formed, indicating that the FPD 100 is in a normal working status.
Most of the light beams provided by the indicator lamp 191 do not emit from the FPD 100. The amount of light beams that form the indicating pattern is quite limited. As a result, the indicating pattern may not be sufficiently visible or clear, and a user may not be aware of the true working status of the FPD 100. This is particularly liable to occur when the FPD 100 is used in a bright environment.
It is therefore desired to provide a key switch system that can overcome the above-described deficiencies, and an FPD employing such key switch system.